Verruca(?) - 4 day treatment?

I finished my run yesterday with a sore foot, which at first I thought was a blister albeit on a part of my foot that I've never blistered on before.

When I was in the shower the area around a little black spot was slightly swollen and it looked like I had a splinter. I tried to stroke it out with tweezers but to no avail.

I put some magnesium sulphate (drawing solution) on it with a plaster and waited a few hours. I then had another look and a squeeze and the skin that had built up around it (maybe due to the drawing solution) was looking like dead skin. I managed to get to near the splinter but still couldn't get any purchase on it and then I thought maybe it was the root of a Verucca.

Any other ideas? This morning it had died down a bit but sore so I've had savlon on it today as I'm concerned it may get infected.

Are tehre any tell-tale signs to say its definitely an early verucca as opposed to s amll and stubborn splinter?

Does sound like one, I've had a few generally brought home from school by the kids, my advice is to leave well alone and it should clear up on its own unless it's in a particularly vulnerable place, I've always found poking around with them makes them sore.